Conventionally, there is known a socket for electrical parts which is configured so as to hold an IC package to be attachable and detachable in an IC package accommodation portion on a socket body, and electrically connect terminals formed on a lower surface of the IC package with the external electric circuit (e.g. an electric circuit board for an electric test of the IC package) using contact pins (e.g. probe pins) accommodated in the socket body (refer to the patent document 1 described below).